Electric heater



Jan. 28, 1947.

J. R. CAMPBELL ELECTRIC HEATER Filed March 22, '1943 Inventor: James, FiCampbell,

His AbtOT-heg lllI Il ,fl

Patented Jan. 28, 1947 ELECTRIC HEATER James R. Campbell, Ontario,Calif.. assigner to General Electric Company, a corporation of New YorkApplication March 22, 1943, Serial No. 480,003

Claims.

1 This invention relates to electric heaters, such as an `electricallyheated appliance like a. flatiron, more particularly to electric heatersof this character which are provided with temperature responsive meansfor automatically holding a preselected temperature in the heateddevice, and it has for its object the provisionof means for givy ing asignal when the device is at the properI temperature set by thetemperature responsive means.

More specically, this invention contemplates th provision of an-improvedelectrically heated device of the thermostatically controlled type whichis provided with a signal which will give indication showing when theheated device `is or is not in the temperature range for whichthethermostat is set. In other words, the sig'r'ialA 1de# Avice iscontrolled to give a signal when the temperature of the heated devicerises and substan- Vtially attains the temperature set by the thermostatand'thereaiter gives a signal continuously 'while the thermostat cyclesbetweenv the low and 'high limits of its normal temperature amplitude inorder to hold the temperature of the device substantially constant. Aslong as the thermostat operates within this range the signal is givencontinuously so that the operator knows that the temperature of thedevice is within the range set bythe thermostat. But if for any reason,such as by echange in the temperature setting of the thermostat, theinstant temperature of the device is either above or below the limits ofthis v range, the signal goes olf, indicating that the heated device isnot at the proper temperature.

In accordance with this invention in one form thereof, the signal deviceis controlled by the movements of the thermostat which is provided tocontrol the energization of the device to control itstemperature. As thethermostat moves responsively -to a rising temperature in the device itfunctions first to cause the signal device to givean indication, andthen it functions to deenergize the heating element of the device;subsequently, it cycles between the low and high limits of itstemperature amplitude to reenergize and deenergize the heating elementto hold the temperature in the device. All of this time it controls thesignal device to give a continuous signal indicating that the heateddevice is Within the proper temperature range.` If the .temperaturesetting of the device be changed or if for any other reason the instanttemperature 0f the device is not within thedesired temperature range,the

' thermostatoperates the signal to shut off its indication, therebyvshowing that'the device is not at the proper temperature.

For a. more complete understanding of this invention, reference shouldbe had to the accompanying drawing in which Fig. 1 is a verticalsectional view taken through control means for a heated device arrangedin accordance with this invention; Fig. 2 is a plan view of the deviceshown in Fig. 1, parts being broken away so as to illustrate certaindetails of construction; Fig. 3 is a sectional view taken through theline 3-3 of Fig. 1 and looking in the direction of the arrows; Fig. 4 isa, sectional view taken through the line 4-4 of Fig. 1 and looking inthe direction of the arrows; Figs. 5 and 6 are fragmentary sectionalviews of a portion of the control device shown in Figs. 1-3, andillustrating certain elements in different operative positions in thetwo figures respectively; Fig. 7 is a diagrammatic view illustrating theheating element of the heated device, the signal device, and certaincontrol elements therefor, all arranged in accordance with thisinvention; and Fig. 8 is a vertical sectional view taken through anelectric flatiron provided with the control device shown in Figs. 1-7.

Referring to the drawing, this invention has been shown in one form asapplied to an electrically heated flatiron (Fig. 8). This iron comprisesa sole plate I0. Cast Within the sole plate I0 is an electrical heatingelement II of the sheathed type; as shown in Fig. 8, this element I I isprovided with a. helical resistance conductor I2 which is mounted withinan outer metallic casing I3 and which is held in spaced relation withreference to the casing I3 by a mass I4 of heat conducting. electricallyinsulating material, such as magnesium oxide.

The signal device for indicating when the sole plate I0 is within theproper operating temperature range consists of an electric incandescentlamp I5. In the flatiron application shown in Fig. 8, the lamp may belocated Within the rear standard of the handle I6 back of a window I'I.The window preferably will be covered by glass which will have adistinctive color such as red.

The energization of the heating elemem-I I2 and that of the signaldevice I5 is controlled by means of a temperature responsive member I8,which preferably and as shown will be of the bimetallic lcontact 3|bottom wall 28 and a pair of side walls 2l and 22; it also has a topwall 22a. The casing'is clamped to the sole plate I0 by means of screws22h. The

left-hand end of the bimetal element section |811,

l as viewed in the drawing, is clamped to the bottom wall 20 by means ofa rivet 23. The other end of the thermostatic blade I8 is free to move11p-` ward'ly and downwardly in the casing responsively to temperaturechanges. When the temperature of the blade rises the free end movesupwardly,

whereas when it cools the free end moves down,- wardly.

l The blade I8 controls suitable switching mechanism which is mountedwithin the casing I9, and which controls'the energization o f theheating element I2 and the signal lamp I5, This.

switching mechanism comprises a Vswitch armis secured to the top wall bymeans of a scr w Cooperating with the xed contacts 33 and/ 34 are a pairof contacts 45 and 46. These contacts are mounted on the opposite endsof a rocker arm 4,1 which is pivoted intermediate its, ends to the endvo'f the switch arm 24 opposite the end of this arm that is connected tothe adjusting post 28.- A compression spring 48 bears on the rocker armto the left of its pivotal mounting on the switch arm, as viewed in thevarious g- 1 ures, for biasing the contact 45 into engagement with itsxed contact 35. `This spring, as shown, v is inserted in an aperture 49provided for it in the insulator, and has its two end s received in`holding studs 50 and 5|, respectively, the former 24 which has a pairof spacedapart side meml 28a which may be rotated so as to adjust the'vertical position ,of the post, and hence, the'posl-V tion of thepivoted end of the switch `arm 24 with reference to2` the thermostatlcblade I8. This is for the purpose of adjusting the temperature settingofthe control device'.v The Abushing 28 is provided with an adjustmentknob 28h outside of the iron shell, as shown.V The transverse pin 23 issufciently long to extend through openings 28e provided in the oppositeside walls'l 2| and 22'of the casing. These openings, as shown, arevertically elongated to provide for the vertical= adjustment of thepost. In other words,.the pin 29 is a oating .cross-member..

The -transverseplate 21 carries an electrical which coacts withVacontact 3 2 mounted on theA movable end ofthe thermostatic blade I8.The switching mechanism V:further comprises a pair of spaced-apart xedcontacts 33 and 34 which are mounted upon the bottom wall of the casingI9.- As shown more clearly in Fig. 3. these contacts are mounteddirectly on conducting plates 35 and 36 which are electrically insulatedfrom the bottom wall by electrically insulating sheets 31 formed of anysuitable. electrically insulating material, such as mica. The conductingplates 35 and. 36 and the electrically insulating.y Ysheets 31 areclamped against the bottom plate 28 by means of anelectricallyinsulatingv block 38, as clearly shown in Fig. 4. It will beobserved that this block has an inverted U shape, the two opposed'arms38a The left-hand ends being mounted in the upper vend of the aperture49 and the latter being mounted upon the rocker 41.' Moreover, there isa suitable stop 52 which is mounted on the insulator above the contact46 carried by the rocker. This stop vfunctions to limit theupwardmovement of the contact'46 with reference to its fixed contact 34.

The various contacts are electrically interconnected with the heater I2and the signal device- I5, and the system is connected with a suitablesource of electrical supply 53 indicated diagrammatically in Fig. '1.That is, thecontact 3| is of the block functioning to clamp theconducting plates and insulating sheets against the bottom wall, vandfurther to hold the two plates in their properoperative positions.

electrical connections are madf The insulator is secured in position tothe topwall 22a by means of a bracket 4| which has a 'section 42extending downwardly into a recess 43 provided for it in the top of theinsulator and which electrically interconnected through the switch arm2-4 with the two contacts 45 and 46 on the rocker 41; the contact 32 onthe thermostat is electrically connected to one terminal of the signallamp I5, the opposite terminal of which is connected to one terminal ofthe heater I2 and to one side of the supply source 53; fixed contact 33is electrically connected through its post 39 withl the opposite side ofthe supply source 53; and the fixed contact 34 is electrically connectedthrough its post 40 to the other side of the heater I2, as shown. Aresistance 54v is connected in series with the lamp I5 so that a lampwith a low voltage ilament may be used. 1 j

When the iron is cold, the thermal blade I8 is in its position shown inFigs. 1 and 7. Now if the iron be plugged into fthe supply source 52,the heating `element I2 'will be energized through a circuit which maybe traced from the upper conductor of the supply source, Athrough theheating element I2, through the closed contacts 34 and 46, through therocker arm 41, and thence through the closed contacts 45 and 33 to thelower conductor of the supply source; the signal lamp I5 at this time isdeenergized .because the contacts 3| and 32 are open.

Therefore, the heating element I2 wi11 apply heat to the sole plate I0'and elevate its temperature. As the vtemperature of the sole plate I0rises, the' thermal bar I8 moves upwardly from its position shown inFigs. land 7 toward its position shown in Fig. 5. When the sole plate I8attains substantially the high temperature set by the thermostat, thethermostat I8 will' move its contact 32 into contact with the contact 3|on the switch arm 24, which operation will energize the signal lamp I5from the upper conductor of the supply source, through the signal lampI5, the resistance 54, closed contacts 3| and 32, switch arm 24, rocker41, and thence through the closed .contacts 45 and 33 tothe lowerconductor of the supply source. The heater I2, however, remainsenergized, and the temperature of the sole plate continues to rise, andas a result the thermal bar continues to riseand will move the switcharm 24 upwardly, as shown in Fig. 5. In.

lowinguthe deenerglzation of the heating element I2, the sole plate Iwill cool andthe thermostat bar will move downwardly to permit thecontact 46 to reclose contact 34 which will reener- 'Ihisoperation, of j-desired low temperature the I -have moved down sufliciently far topermit the contacts-46 and 34 to reclose, which operation will againreenergize the heater I2. Then the thermostat will move upwardly anddownwardly v responsively to increases and decreases in the temperatureof the sole 'plate so as to cycle the contacts 46 and 34 between openand closed posigize the heating element I2. Following this, thevthermostat again will be heated to move upwardly to open the contact 46and deenergize the heater I2. In this way, the thermostat bar I8 willoscilstant temperature in the iron; that is. when the temperature of theiron falls responsively to the deenergization of the heater I2 and thetemperature of the bar falls by a predetermined amount to a lower value,the heater I 2 will be reenergized, and when the temperature of the barrises by a predetermined amount to a higher value the heater will bedeenergized. The range between the low and high temperatures at whichthe thermostatic bar operates in this Way is known as its temperatureamplitude And while the thermostat operates through its amplitude, thecontacts 3I and 32 will remain closed and the'contacts 33 and 45 will bebiased closed so that ythe signal lamp I5 will be continuouslyenergized, thereby'indicatlng that the iron is at the lpropertemperature. This operation is true for any particular temperature setby the knob 28h.

Now, if the iron be operating at a selected tem-` perature, and it bedesired to operate the iron at a higher temperature, the adjustment post28 will be moved upwardly from the thermostat I8.

bend upwardly, and the aforo-described operaJ tion will be repeated;that is, the thermostat will close the contacts 3| and 32 to energizethe signal lamp I5, and after this, it will osclllate the contacts 46and 34 between open and closed positions to control the energization ofheater I2 to hold the new temperature. The signal lamp againcontinuously indicates that the iron is operating within the propertemperature range.

'If now it should be desired to set the iron to operate at a lowertemperature, the adjustment post 2B will be lowered. This operation willfulcrum the switch arm 24 on the contact 32 of the thermostat andelevate the rocker 41 to cause it to engage the stop 52 to thereby pivotthe rocker` with relation to the switch arm and open the contacts 4-5and 33, as shown in Fig. 6. When these contacts open,the energizingcircuit for the signal lamp is broken, and the signal is shut off toshow that the irori is not now at the correct temperature for thesetting. AFollowing this, the sole plate will cool down and so will thethermostat I8 which will deect toward the bottom plate 2|). Just priorto the time that the sole plate reaches the desired low temperature, theswitch arm 24 will have swung downwardly sumciently far to permit thecontacts 45 and 33 to reclose. This operation will reenergize the signallamp I 5. And

following this, when the iron has attained the As the solel platetemperature rises, the thermostat I8 will;y

tions to hold the desired low temperature, all as fully describedbefore. All of this time, however,

the signal lamp I5 will be energized through the ,l

contacts 3i and 32 and the contacts 33 and 45.

Therefore, for any particular setting of the thermostat, and as long asthe iron is operating within the range of the temperature amplitude ofthe thermostat, the signal lamp I5 will be energized to indicate thatthe iron is at the proper operating temperature. If for any reason thetemperature of the sole plate IIJ be below or above the desired range,the signal lamp will be deenergized thereby `indicating that the iron isnot at the proper temperature.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited theretovsincemany modifications may be made, and I therefore contemplate by theappended claims to cover any such modications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates ls:

l. In an electrically heated device having a heating element, a switchconnected to control the energzation of said heating element, athermostat, a lever connected to said switch to operate it, said leverbeing engaged by said thermostat as it heats up so that it is moved toopen said switch to deenergize said heater at a predetermined hightemperature and when said thermostat cools said lever is moved toreclose said Switch to reenergize said heater, said switch thereafterbeing operated to open and close to deenergize and reenergize saidheater t0 hold a substantially constant temperature in said device assaid thermostat cycles responsively to heating and cooling anelectrically responsive signal device, a second switch operatedresponsively to the interengagement of said lever and thermostat forcausing said signal device to give a signal continuously as long as saidthermostat cycles to hold said substantially constant temperature, meansfor adjusting the position of said lever to adjust the temperature heldin said heated device, and a third switch for controlling said signaldevice controlled by the operation of said lever so that when said leveris adjusted to a temperature setting lower than the instant temperatureof said heated device said third switch is operated to deenergize saidsignal device irrespective of the fact that said thermostat and leverare in engagement. v

2. In an electrically heated device having a heating element, athermostat responsive to the temperature of said heated device, a signallamp, a control switch mechanism for controlling the energization ofsaid heating element and said signal lamp having a first set of coactingcontacts connected in the energizing circuit of said heating-element,and a' second set ,of coacting contacts connected in the energizingcircuit of said lamp, one contact of said second set being movable bysaid thermostat and the other contact of said set being mechanicallyinterconnected with one of the contacts of said first set, saidthermostat when it heats and deflects moving said one movable contact ofsaid second set into engagement with device is above that set by saidlever.- 1

A 7 its coacting contact to energize said lamp, and said rst set ofcontacts being operated by the mechanical connection between said othercon- A responsive to the temperature of said heated device, a controlswitch mechanism for controlling the energization of said heatingelement and said signal lamp having a rst set oi normally closedcoacting contacts connected in both the energizing circuits of saidheating element and lamp,

i a lever connected to one of said contacts to control the operation ofsaid contacts, a second set of coacting contacts connected in theenergizing circuit kof said lamp, one contact of which is movable bysaid thermostat and the other of which is mounted on said lever 'and bysaid lever is electrically and mechanically interconnected with one ofthev contacts of said rst set, the two sets jointly controlling saidsignal -lamp so v'that when said thermostat heats and thereby de-`ilects it moves said one movable contact into engagement with itscoacting contact to energize said lamp, said switch mechanism a1so'having a interengagement of said second setof contactsb and saidthermostat moves said lever responsively to its heating and cooling,means for aldljusting the position of said lever to adjust thetemperature settingof said heated device, and saidsecond set of contactsbeing operated to open said lampenergizing circuit to deenergize saidlamp when the temperature of said heated 4. In an electrically heateddevice having a heating element, a signal device, energizing circuitsior said heating element and signal device, switch means for controllingsaid circuits having a, pair of switch elements, one for controllingthecircuit of said heating element and the other for nal lamp, controlmeans for said heater and lamp comprising, switch means for controllingthe energization of said heater, an operating member for said switchmeansfor operating it to deenergize and reenergize said heater respon-`sively to movements of said member, a pair of cooperating contacts forcontrolling the energizetion of said signal' lamp, one mounted on saidoperating member and the other on said thermo- 'l stat, the latter beingmoved into engagement with the former when said thermostat deflectsresponsively to temperature increase and when moved into engagementfunctioning to cause said signal lamp to give a signal, and thereaftermoving said operating member to deenergize and reenergize said heater tohold a substantially constant temperature' in said device as saidthermostat deects in opposite directions as it heats and cools, saidinterengaged pair' of contacts all the while continuing to cause said.signal lamp to give said signal, adjustable means for varying thepositional relationship between said thermostat and operating member tochange the temperature setting of said control means and thereby thetemperature held in said device, and additional switch means forcontrolling said signal lamp controlled responsively to the operation ofsaid adjustable means so that when said adjustable means is operated toset a lower temperature than the instant temperature of said device saidadditional switch means is operated to cause said signal device to ceasegiving said signal, irrespective of the 4fact that said pair of contactsare in engagement.

6. In an electrically Vheated device having va heating element, a switchfor controlling the energization of said heating element, 'a thermostatresponsive tothe temperature of said device,

controlling the circuit of said signal device, and y alsol having athird switchvelement common to the circuits of both said heating elementand sig nal device, a thermostat responsive to the temperature of saidheated device controlling said switch means to operate said switchcontrol element for said heatingelement circuit to deenergize andreenergize it so that said heating element holds a substantially uniformpreselected l temperature in said device by the thermostat cycling in anormal temperature amplitude asthe device heats and cools, to voperatesaid switch control element for said signal device circuit to cause saidsignal device to give a signal continuously when the thermostat operateswithin the limits of said normal temperature amplitude, and said asingle movable member connected to said switch to 'operate it so thatwhen said member is moved in one direction it opens said switch todenergize said heating element and when moved in the other'direction itrecloses said switch to, reenergize said heating element, a contact onsaid movable member and a coacting contact on said thermostat, saidthermostat moving said coacting contact into engagement with the contacton said movable member as said thermostat heats up so that said movablemember is moved by said contacts -insaid one direction to operate saidswitchto deenergize said heater and then as said thermostat cools movesin the other directiontooperate it to 4reenergize said heater, andthereafter is moved to deenergize and reenergize s'aid heater ina seriesof cycles to hold a substantially constant temperature'in said device,

' all .by the interengaged pair of contacts which are held in"engagement and operated by said thermostat as it heats and cools, anelectroresponsive gized to cause said signal device to give a signalthermostat operating said third switch control element for said heatingelement and signal device to a deenergizing position when thetemperature of the device is above the temperature setting of saidthermostat to break the circuits of both said signal device and heatingelement.

5. In an electrically heated device, a heater for heating said device, athermostat responsive to the temperature of said device, an electricsigwhen said contacts are' moved into engagement with each other and allthe while said control niember is operated by them in said series ofcycles to hold said substantially constant temperature in said device.

7..In an electrically heated device provided with a heating element, anelectric sign-al device, and control means for said heating element andsignal device comprising, a thermostat operated responsively to thetemperature of said device, a movable switch arm, cooperating contactson said switcharm and thermostat respectively controlling said signaldevice, two pairs of cooperating contacts one contact oi each pair beingmovable by said switch arm, the iirst set of said pairs controlling saidsignal device and heating element, and the second set controlling saidheating element, andsaid thermostat when operating responsively to arising temperature condition in said device causing its contact toengage with its cooperating contact on said switch arm to energize saidsignal device to give a signal through said first set of contacts andthen moving said switch arm to open said second set of contacts todeenergize said heating element upon said device attaining saidpredetermined temperature and subsequently cycling said second setbetween A opened and closed positions to hold substantially saidtemperature, the signal device all the while remaining energized to giveits signal through said cooperating contacts on said thermostat andswitch arm and said iirst set of contacts, and means controlling theoperation of the movable lpair of contacts of the two sets responsivelyto signal device comprising, a movable switch arm,

l and a rocker arm pivoted to said switch arm, a

Y on said thermostat, said third set controlling said device comprising,a thermostat operated responsively to the temperature of said device. amovable switch arm, a pair of cooperating contacts controlling saidsignal device, one on said thermostat an'd the other on said switch arm,a second pair of cooperating contacts controlling said signal devicejointly with said iirst pair and also controlling said heating element,a third pair of cooperating contacts controlling said heating element,one each of said second and third pairs being mounted on said switch armfor movement relatively tojsaid switch arm and being movable by saidswitch' arm with reference to the other contacts of said pairs, and saidsecond contacts on said switch arm being mechanically interconnected,biasing means holding said second pair kof 'contacts together, saidthermostat upon moving responsively to a rising temperature in saiddevice causing its contact to engage its cooperating contact on saidswitch arm to energize said signal device to give a signal through saidsecond pair of contacts, and upon further movement moving said switcharm to open said third pair of contacts to deenergize said heatingelecontact of said third pair away from its associated contact so thatwhen said contact engages said stop, said movable contact of said secondpair is moved away from its associated contact by the connection meansbetween it and the movable contact of said third pair, whereupon saidsignal device is deenergized to stop its signal.

9. In an electrically heated device provided with a heating element, asignal device, and means for controlling said heating element and signaldevice jointly with said iirst set, said thermostat moving when thetemperature of said device rises to cause itscontact to engage that onsaid switch arm to energize said signal device to give its signalthrough said first set of contacts and upon further movement moving saidswitch arm to tend to separate said contacts on said rocker arm fromtheir cooperating contacts, said biasing means however holding saidfirst set closed to maintain the energization of `said signal device tocontinue its signal, and the third set opening to deenergize saidheating element, said thermostat subsequently oscillating said arm asthe thermostat cools and heats to reclose and open said third set tohold a substantially constant temperature in said device, means forshifting the position of said switch arm to change the temperature heldin said device, and a stop for limiting the movement of the movablecontact of said third set away from its iixed contact by said switch armso that when the temperature of said device is above that set, saidsecond set of contacts are opened to deenergize said signal device toshut off its signal.

10. In a natiron and the like provided with a heating element, a signaldevice, and control means for said heating element and signal devicecomprising.y a thermostat responsive to the temperature of said iron, aswitch arm, means pivoting one end of said switch arm, means for ad--justing the position of said last-named means to adjust the position ofsaid switch arm, a first contact on said switch arm located between itsends, a rocker, means pivoting said rocker to the other end of saidswitch arm, a second contact on said thermostat coacting with said firstcontact, third and fourth contacts on the two ends of said rocker, fifthand sixth fixed contacts cooperating with said third and fourth contactsrespectively, a spring biasing said rocker tc hold said third and fifthcontacts together, said thermostat when heated moving said iirst contactinto engagement with said second contact and upon further movementshifting said switch arm to open said fourth and sixth contacts, saidspring functioning to hold said third and fifth contacts closed, -a stopfor engaging said rocker to limit the movement of said fourth contactaway from said sixth contact so that if said thermostat continues itsheating movement or said switch arm is adjusted for a lower temperaturethan the instant temperature of said device said fourth contact engagessaid stop to move said rocker to open said third and ilfth contacts, anenergizing circuit for said signal device controlled jointly by saidill-st and second and said third and fth contacts, and an energizingcircuit for ,said heating element controlled by said third and iifth andsaid fourth and sixth contacts.

JAMES R. CAMPBELL.

